Metalworking lubricant



Patented Feta. 1G, 1%53 TENT FFICE 2,628,197 nsrsrwoanmo LUBRICANTRobert B. Killingsworth, Roslyn, N. Y., assignor to Socony-Vacuum OilCompany, Incorporated, a corporation of New York No Drawing. ApplicationAugust 1'2, 1951i, Serial No. 180,103

5 Claims.

like. By way or" conventional designation in the art, the lubricatingcompositions with which the present invention is concerned fall withinthe class commonly referred to as soluble oils.

These, as is well known, comprise a lubricating oil having dissolved ordispersed therein an emulsifying material imparting to the oil acapaclty for substantial aqueous dilution to form a stable oil-in-wateremulsion.

The emulsion so formed is utilized by pouring over the tool and the workin a steady stream, and functions to dissipate the heat from both thetool and the work; improve the quality of the surface produced;lubricate the surfaces in contact between the tool and the work; washaway the chips; and to provide lubrication between the chip and thetool, thus reducing the pressure of the chip on the tool. Oil emulsionsare normally used where roughing cuts are being made. In roughing cuts,the primary obiect is to remove material and the quality of the surfaceproduced has been considered secondary. However, since in the subsequentfinishing out only a very small amount of material is removed, thepreceding rough out should not leave the work in such a condition thatthe finishing cut will not remove the scars left by the rough cut.Therefore, the nature of the cutting oil used during the roughing outshould be such asto improve the quality of the surface being worked.There is ordinarily an enormous pressure exerted between the cuttingedge of the tooland the metal being machined and in addition, due to theinherent resiliency of the metal, heavy pressures are maintained betweenthe work and the surface of the tool just under'the cutting edge andbetween the chips and the surface of the tool just back of the cuttingedge. Therefore, it is requisite that alubricant be provided which iscapable of aiiording a high load-carrying film oi lubricant between thecutting tool and the work being machined.

It has heretofore been the practice to improve the film strength ofsoluble oil lubricants by the incorporation therein of various compoundsof sulfur, phosphorus, chlorine, fatty materials or combinationsthereof. Such additive materials, however, have not been found to beentirely satisfactory and in addition to being comparatively expensivehave the accompanying disadvantages of tendency toward corrosion andrancidity particularly where the soluble oil containing the same isexposed to the atmosphere for an extended period of time, either beforeuse or during use in a circulating type system in which the same oil iscontinuously recycled over the metal being worked.

It is accordingly an object 01' the present invention to provide animproved composition adapted for lubrication during metal processingoperations, free of the aforementioned disad vantages. A further objectis to provide an improved metal prccessing lubricant and particularly alubricant which is stable and non-corrosive toward metals. A stillfurther object is the provision of a low cost, commercially attractivemetal lubricating composition.

The above and other objects which will be apparent to those skilled inthe art are attained in accordance withthe present invention, whichcomprises a soluble oil containing an organophilic bentonite. It hasbeen found that the resulting compositions are efiective lubricants formetal processing operations and aiiord lubricants of high film strengthuseful in various metal 'machining operations, including cutting,drawing, tapping, milling, and the like.

Bentonite, in its natural state, is a highly hydrophilic mineralconsisting principally of montmorillonite, which is a hydrous aluminumsilicate with a micaceous structure and an exceptionally small ultimateparticle size. It occurs customarily as the salt of a moderately strongacid in which the cation i predominately sodium. It has heretofore beenknown that bentonite may be converted into a hydrophobic andorganophilic condition by the introduction of long chain hydrocarbonradicals into the surface of the montmorillonite clay particles. Thenature and preparation of organophilic bentonites has been described indetail by J. W. Jordan in the Journal of Physical and Colloid Chemistry,vol. 53 No. 2, 1949, pages 294-306. Briefly, however, the preparation ofan organophilic bentonite. involves hydration of the montmorillonite ina verydilute dispersion to separate the unit particlesand to achievecomplete removal of non-clay impurities. This. step is resorted to sincemost montmorillonite in the crude state contain relatively largequantities of quartz which, if allowed to remain, would impart anabrasive character to the resulting product. The reactive sodium atomsof the clay particles are then replaced by organic cations and theproduct is washed,

.filte'red, and dried. By proper choice of the organic cation, theproperties of the resulting bentonite product can be controlled.Generally, for imparting organophilic properties to the bentonite, anorganic ammonium compound having a hydrocarbon chain of at least carbonatoms is employed. Increasing the chain length of the ammonium compoundgives a product of increasing organophilic properties. The ammoniumcompounds are usually converted to the form of salts before use. Thus,organophilic bentonites have been prepared by the reaction of bentonitewith various aliphatic ammonium salts, including the salts of long chainamines, and quaternary ammonium salts having one or more long aliphaticchains. The resulting products are generally referred to as alkylammonium bentonites and are more commonly known to the trade asBentones. The figure following the trade name Bentone indicates thenumber of carbon atoms in the hydrocarbon radical attached to thesilicate structure of the bentonite. Thus, Bentone 18 designates anorganophilic bentonite having a chain of 18 carbon atoms. Thesebentonite products have substantially no afiinity for water but becauseof the long hydrocarbon chains coating the particles and the plateletsof clay, they are subject to ready dispersion in organic liquids.

It has been discovered, in accordance with the instant invention, thatthe machining efiiciency of soluble cutting oils is considerablyenhanced by the presence therein of an organophilic bentonite. Thecharacterizing ingredients of the presently discussed compositionaccordingly include a soluble oil capable of forming an oil-in-wateremulsion, an emulsifying agent present in a proportion sufficient toform a substantially stable emulsion and an organophilic bentonite.

As an example of the soluble cutting oil emulsions of this invention,the following is representative:

EXAMPLE Weight per cent Mineral oil 10.0 Bentone 18 10.0 Oleic acid 4.5Triethanolamine 1.5 Water 74.0

The procedure for the preparation of the above emulsified cuttinglubricant is as follows: Individual Bentone is dispersed in the mineraloiloleic acid mixture with an electric propeller-type mixer. The mixtureis added to the water containing triethanolamine and homogenized in ahigh-pressure homogenizer. Heating is not necessary.

The emulsifier capable of forming oil-in-water emulsions utilized in theinstant compositions may be any of the usual emulsifiers so employed. Avery typical and usual material of this type is a soap of a long chainfatty acid. Thus, in the above illustrative composition, the oleic acidand triethanolamine in combination formed a soap which served as theemulsifier. Likewise, sodium or potassium soaps of animal and vegetablefats may similarly be employed. Numerous other common emulsifying agentssuch as the alkali soaps of rosin, oleic acid, naphthenic acids, etc.,may also be used. These emulsifying agents may either be prepared insitu as the amine soap above or employed in already prepared form. Theproportion of the emulsifying agent may be varied widely and will belargely dependent upon the efiectiveness thereof as an emulsifyingagent. For

4 practical purposes, it will be understood that the emulsifying agentis present in a minor proportion sufiicient to provide a substantiallystable emulsion.

Although a wide range of mineral lubricating oils may be employed as thebase for the soluble cutting oils described herein, in general the baseoil comprises an oil having a Saybolt Universal viscosity at F. in therange of from about 40 to about 200 seconds and an A. P. I. gravity of19 to 36. However, in preparing the present compositions, it ispreferred to use a light oil as the base, that is, one having a gravityin the range of from 20 to 36 A. P. I. and a viscosity at 100 F. of from40 to 100 seconds.

The concentration of organophilic bentonite in the soluble oilcomposition is such as to improve the machining efficiency thereof andmay be varied widely in accordance with the use to which it is to beput. Where the emulsion is to be employed as a coolant, as well as alubricant and applied by a circulating pump or the like, theorganophilic bentonite should ordinarily be present in a concentrationof from about 0.1% to about 5%. Where the lubricant is to be applied tothe work and tool by brushing or the like, the organophilic bentonitecomponent will be present in the emulsion in a concentration ofapproximately 10% by weight. Generally, the emulsion will be marketed asa concentrate to be further diluted for use as required. In suchconcentrate,

the organophilic bentonite component will usucomprise the combination ofrecited components in the following proportions:

Preferred Broad Range Range Percent by Pcrccn! by Weight ll 'ei htMineral Lubricating Oil ill-25.0 5.015.0 Organophillc Bentonite 0.120.0ao-nn Emulsifier 0.510.0 I 4.0- (i 0 Water I 94.4-45.0 I 93. 0437. '1

An evaluation of the tapping efficiency of a typical soluble oilemulsion with and without an organophilic bentonite was obtained bySubjecting samples of the oils to the following test:

Tapping test In the measurement of tapping efficiency of an oil, aseries of holes is accurately drilled in a test metal, namely, SAE 1020hot rolled steel. These holes are subsequently tapped with a series oftaps in a drill press equipped with a table, which is free to rotateabout the center, being mounted on ball bearings. A torque arm isattached to this floating table and this arm in turn actuates: a springscale so that the actual torque during tapping with the oil beingevaluated is measured directly. The same taps used in evaluating the.test oil are employed in tapping with a standard reference oil, whichhas arbitrarily been assigned an efilciency of 100 per cent. The averagetorque for the test oil i compared to that of the standard and arelative efliciency is calculated on a percentage basis. For example:

Torque with standard reference oil 19.3 Torque with test oil 19.8Relative efficiency of test oil The results of the above-described testin evaluating lubricants of the following composition are set forthbelow:

10.0% mineral seal oil 4.5% oleic acid 1.57 triethanolamine 84.0 a water-l Tapping eiiiciency, percent.

10.07 Bentone l8 10.0%; mineral seal 0'1 4.5% oleic acid. 1.5%triethanolarn' 74.0% Water Tapping efiiclency, percent-l From theforegoing, it will be seen that the presence of an organophilicbentonite in the soluble oil composition enhanced the tapping efficiencythereof. It will further be seen that a 1:10 dilution of thecompositions with water indicated a marked improvement of theBentone"-containing soluble oil as compared with the diluted compositionwherein Bentone was absent. Without being limited by any theory, it isbelieved that in the more concentrated composition, the soap content wassuflicient to provide fairly good tapping emciency, but as thecompositions were diluted, the concentration of soap decreased and theimproving benefits of the organophilic bentonite became more apparent.In every instance, improvement in machining efficiency was noted when anorganophilic bentonite was present.

It is to be understood that the above description is merely illustrativeof preferred embodiments of the invention of which many variations maybe made within the scope of the following claims by those skilled in theart without departing from the spirit thereof.

I claim:

1. An aqueous soluble cutting oil emulsion consisting essentially ofmineral lubricating oil dispersed in water, an oil-in-water typeemulsifier present in minor proportion sufficient to form asubstantially stable oil-in-water emulsion and between about 0.1 percent and about 50 per cent by weight of an organophilic bentonitecharacter- As is (1 part product, 10 parts water) As is (1 port product,10 parts water) 6 ized by a hydrocarbon chain of at least 10 carbonatoms.

2. An aqueous soluble cutting oil emulsion consisting essentially of amineral lubricating oil dispersed in water, stabilized with anoil-in-water type emulsifying agent present in a minor proportionsuflicient to form a substantially stable oil-in-water emulsion, andcontaining an organophilic bentonite having a hydrocarbon chain of atleast 10 carbon atoms present in amount sufficient to improve thetapping efficiency of said emulsion.

3. An aqueous soluble cutting oil emulsion consisting essentially of amineral lubricating oil dispersed in water, stabilized with anoil-in-water type emulsifying agent present in a minor proportionsufiicient to form a substantially stable oilin-water emulsion, andcontaining an organephilic bentonite having a hydrocarbon chain of atleast 10 carbon atoms, said organophilic bentonite being present in anamount sufficient to improve the tapping efficiency of said emulsion.

4. A composition capable of forming a substantially stable aqueousemulsion comprising the following components:

Per cent by weight Mineral lubricating oil 5.0-25.0 Organophilicbentonite having a hydrocarbon chain of at least 10 carbon atoms(Ll-20.0 Emulsifier (oil-in-water type) 0.5-10.0

Water 94.4-45.0

5. A composition capable of forming a substantially stable aqueousemulsion comprising the following components:

Per cent by weight Mineral lubricating oil 5.0-15.0 Organophilicbentonite having a hydrocarbon chain of at least 10 carbon atoms53.0-12.0 Emulsifier (oil-in-water type) 4.0- 6.0

Water 83.0-67.0

ROBERT B. KILLINGSWORTH.

REFERENGES CITED lhe following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,517,577 Olsson Dec. 2, 19242,291,066 Waugh July 28, 1942 2,531,440 Jordan Nov. 28, 1950

1. AN AQUEOUS SOLUBLE CUTTING OIL EMULSION CONSISTING ESSENTIALLY OFMINERAL LUBRICATING OIL DISPERSED IN WATER, AN OIL-IN-WATER TYPEEMULSIFIER PRESENT IN MINOR PROPORTION SUFFICIENT TO FORM ASUBSTANTIALLY STABLE OIL-IN-WATER EMULSION AND BETWEEN ABOUT 0.1 PERCENT AND ABOUT 50 PER CENT BY WEIGHT OF AN ORGANOPHILIC BENTONITECHARACTERIZED BY A HYDROCARBON CHAIN OF AT LEAST 10 CARBON ATOMS.